1. Field of the Invention
This invention relates to crop spraying and especially to valves utilized for dispensing chemicals in a crop spraying apparatus.
2. Discussion of Related Art
An aircraft employed in crop spraying generally carries a boom which runs under the wing of the aircraft. Attached to the boom are some sixty to sixty-four valves. The spray tip out of which the chemical is emitted is attached to the other end of each valve. The conventional valve has an apparatus at one end which contains a rubber diaphragm to prevent the dripping of chemicals by enabling the pilot to effect a positive turn-off. The rubber diaphragms are adnormally bulky and therefore increase airflow or drag thus reducing the planned performance. Also, the rubber diaphragms rupture frequently and have to be replaced quite often. The conventional valve also utilizes a spray tip which is affixed directionally so that adjustment of the spray direction or pattern must be effected by movement of the entire boom to the desired adjustment position. Resetting in this manner requires a great deal of guess work as well as consuming a great deal of effort.
A great many nozzle and valve assemblies have been suggested for use in dispensing fluid. For instance, U.S. Pat. No. 2,683,626, issued July 13, 1954 to Wahlin, shows a spray nozzle with a pivoting head for controlling the width of spraying of ground areas such as fields or the like.
U.S. Pat. No. 3,893,630, issued July 8, 1975 to Bochman et al, includes two housings, one of which includes a cylindrical recessed portion and the other of which includes a cylindrical portion adapted to rotatably mate with the recess.
U.S. Pat. No. 4,068,833, issued Jan. 17, 1978 to Buford, shows a cutting or a welding torch with a swivel-type nozzle which incorporates a gauge or face with markings indicating the angularity of the nozzle axis with respect to the main axis of the torch to allow the operator to set the nozzle at a number of conventional angles.